thunderbolt: Limit USB3 bandwidth of certain Intel USB4 host routers

Current Intel USB4 host routers have hardware limitation that the USB3
bandwidth cannot go higher than 16376 Mb/s. Work this around by adding a
new quirk that limits the bandwidth for the affected host routers.

Cc: [email protected]
Signed-off-by: Gil Fine <[email protected]>
Signed-off-by: Mika Westerberg <[email protected]>

Author: Gil Fine

drivers/thunderbolt/quirks.c

@@ -26,6 +26,19 @@ static void quirk_clx_disable(struct tb_switch *sw)
 	tb_sw_dbg(sw, "disabling CL states\n");
 }
 
+static void quirk_usb3_maximum_bandwidth(struct tb_switch *sw)
+{
+	struct tb_port *port;
+
+	tb_switch_for_each_port(sw, port) {
+		if (!tb_port_is_usb3_down(port))
+			continue;
+		port->max_bw = 16376;
+		tb_port_dbg(port, "USB3 maximum bandwidth limited to %u Mb/s\n",
+			    port->max_bw);
+	}
+}
+
 struct tb_quirk {
 	u16 hw_vendor_id;
 	u16 hw_device_id;
@@ -43,6 +56,24 @@ static const struct tb_quirk tb_quirks[] = {
 	 * DP buffers.
 	 */
 	{ 0x8087, 0x0b26, 0x0000, 0x0000, quirk_dp_credit_allocation },
+	/*
+	 * Limit the maximum USB3 bandwidth for the following Intel USB4
+	 * host routers due to a hardware issue.
+	 */
+	{ 0x8087, PCI_DEVICE_ID_INTEL_ADL_NHI0, 0x0000, 0x0000,
+		  quirk_usb3_maximum_bandwidth },
+	{ 0x8087, PCI_DEVICE_ID_INTEL_ADL_NHI1, 0x0000, 0x0000,
+		  quirk_usb3_maximum_bandwidth },
+	{ 0x8087, PCI_DEVICE_ID_INTEL_RPL_NHI0, 0x0000, 0x0000,
+		  quirk_usb3_maximum_bandwidth },
+	{ 0x8087, PCI_DEVICE_ID_INTEL_RPL_NHI1, 0x0000, 0x0000,
+		  quirk_usb3_maximum_bandwidth },
+	{ 0x8087, PCI_DEVICE_ID_INTEL_MTL_M_NHI0, 0x0000, 0x0000,
+		  quirk_usb3_maximum_bandwidth },
+	{ 0x8087, PCI_DEVICE_ID_INTEL_MTL_P_NHI0, 0x0000, 0x0000,
+		  quirk_usb3_maximum_bandwidth },
+	{ 0x8087, PCI_DEVICE_ID_INTEL_MTL_P_NHI1, 0x0000, 0x0000,
+		  quirk_usb3_maximum_bandwidth },
 	/*
 	 * CLx is not supported on AMD USB4 Yellow Carp and Pink Sardine platforms.
 	 */

drivers/thunderbolt/tb.h

@@ -272,6 +272,8 @@ struct tb_bandwidth_group {
  * @group: Bandwidth allocation group the adapter is assigned to. Only
  *	   used for DP IN adapters for now.
  * @group_list: The adapter is linked to the group's list of ports through this
+ * @max_bw: Maximum possible bandwidth through this adapter if set to
+ *	    non-zero.
  *
  * In USB4 terminology this structure represents an adapter (protocol or
  * lane adapter).
@@ -299,6 +301,7 @@ struct tb_port {
 	unsigned int dma_credits;
 	struct tb_bandwidth_group *group;
 	struct list_head group_list;
+	unsigned int max_bw;
 };
 
 /**

drivers/thunderbolt/usb4.c

@@ -1882,6 +1882,15 @@ int usb4_port_retimer_nvm_read(struct tb_port *port, u8 index,
 				usb4_port_retimer_nvm_read_block, &info);
 }
 
+static inline unsigned int
+usb4_usb3_port_max_bandwidth(const struct tb_port *port, unsigned int bw)
+{
+	/* Take the possible bandwidth limitation into account */
+	if (port->max_bw)
+		return min(bw, port->max_bw);
+	return bw;
+}
+
 /**
  * usb4_usb3_port_max_link_rate() - Maximum support USB3 link rate
  * @port: USB3 adapter port
@@ -1903,7 +1912,9 @@ int usb4_usb3_port_max_link_rate(struct tb_port *port)
 		return ret;
 
 	lr = (val & ADP_USB3_CS_4_MSLR_MASK) >> ADP_USB3_CS_4_MSLR_SHIFT;
-	return lr == ADP_USB3_CS_4_MSLR_20G ? 20000 : 10000;
+	ret = lr == ADP_USB3_CS_4_MSLR_20G ? 20000 : 10000;
+
+	return usb4_usb3_port_max_bandwidth(port, ret);
 }
 
 /**
@@ -1930,7 +1941,9 @@ int usb4_usb3_port_actual_link_rate(struct tb_port *port)
 		return 0;
 
 	lr = val & ADP_USB3_CS_4_ALR_MASK;
-	return lr == ADP_USB3_CS_4_ALR_20G ? 20000 : 10000;
+	ret = lr == ADP_USB3_CS_4_ALR_20G ? 20000 : 10000;
+
+	return usb4_usb3_port_max_bandwidth(port, ret);
 }
 
 static int usb4_usb3_port_cm_request(struct tb_port *port, bool request)